Photo-electrocatalytic performance of poly(3,4-ethylenedioxythiophene)/TiO2 nano-tree films deposited by oCVD/CVD for H2 production

The hydrogen production from photo-electrocatalytic water splitting attracts extensive attention as a direct way to convert solar energy into chemical fuels. In this work, innovative photo-anodes composed of TiO2 which has a preferable growth orientation [211] conjugated with PEDOT as bi-layers are prepared by a dry process strategy, combining oxidative and metalorganic chemical vapor deposition (CVD). Pure anatase, dendritic TiO2 films of variable thickness are obtained at 500°C by varying the deposition time. Increase of films thickness from 474 to 2133 nm results in morphologies that evolve from dense and angular structures to isolated and nanostructured tree-like columns with a concomitant decrease of the charge transfer resistance due to the enhancement of active facets of anatase structure. The PEDOT/TiO2 bi-layer with an overall thickness of 1350 nm and a 50 nm thick upper-PEDOT layer exhibits the highest photocurrent response (0.26 mA cm-2 at 1.8 V/RHE), a fast photocurrent response under illumination, and the best hydrogen yield up to 4.1 µmol cm-2 h-1 with electronic conductivity being three order of magnitude higher than pristine TiO2.